During many total knee replacement (TKR) or total knee arthroscopy (TKA) procedures, the patella is frequently resurfaced, such as with a polymer like polyethylene. Despite this resurfacing, a moderate number of post-TKA patients still experience anterior knee pain and their technetium bone scans can show an increased activity in the patella. This increased activity is believed to be due to overstressed bone.
Some theories exist to explain why the patella is often overstressed following TKA. Since patellar resurfacing components are typically formed from polymer-based materials, like polyethylene, this increases stress transfer to the bone. Patellar resurfacing components tend not to have a metal backing since the inclusion of the metal backing creates other wear problems. Another theory proposed is that the TKA components do not perfectly duplicate normal knee kinematics and this also increases forces on the knee extensor mechanism and the patella. Still another theory is that, if during resurfacing, the patella is resected too thick, too thin, or asymmetrically, this would result in increased strain in the patella bone.
Accordingly, there exists a need for treatments and devices that would strengthen and/or stimulate repair of residual patella bone following TKA, or if the surgeon deems necessary, in conjunction with the TKA procedure. These patellar treatments and devices would ideally avoid the setbacks described above with current treatments and devices, including the high incidence of patellar complications following TKA or TKR procedures.